Optical servo system for a tape drive

ABSTRACT

The optical servo system for a tape drive that functions to align a read/write head with the data tracks written on a recording surface of a tape by reading optical servo tracks that are formed on the back side of the tape. This process decouples the magnetic recording of data on the recording surface of the tape from the optical servo system which makes use of servo tracks formed on the back side of the tape. The data storage capacity of the tape is increased since the entire recording surface of the tape is filled with data tracks and the precise alignment of the read/write head makes it possible to place the data tracks closer together. Regions of contrasting reflectivity or phase are also provided on a surface of the read/write head to enable the optical servo system to view an image of both the read/write head and the entire back side of the tape to thereby align the movable read/write head with the data tracks.

FIELD OF THE INVENTION

[0001] The present invention relates to servo systems for use with tapemedia and, in particular, to a servo system that makes use of opticaltracking features formed on the back side of the tape to enable thesystem to precisely align the read/write heads with the recorded datalocated on the front side of the tape.

PROBLEM

[0002] It is a problem in the field of tape data storage media toaccurately position the read/write heads with respect to the tracks ofdata written on the tape. In longitudinal tape media, the tape typicallycontains a single recording surface on which is written along the lengthof the tape a plurality of parallel aligned tracks of data. In systemsusing high track densities (>200 tracks per inch), the precise alignmentof these data tracks with the read/write heads of the associated tapedrive is accomplished by the use of a plurality of servo tracks writtenon the tape recording surface, interspersed with the tracks of data. Theservo tracks, typically written during the tape manufacturing process,function as a physical reference for the placement of the data trackswhen the data tracks are written on the tape and for reading previouslywritten data tracks from the tape. The position information derived fromthe servo tracks is used by the tape drive to adjust the position of themovable read/write head to enable the accurate reading and writing ofdata to and from the data tracks.

[0003] A problem with this tracking system is that the number of datatracks written on the tape is limited by the need for servo trackswritten on the recording surface to provide position information. Thereis a need to facilitate the development and use of future tape systemswith increased data capacity. This is often accomplished by the increasein the number of data tracks and the amount of data placed in a giventrack. Due to the mechanical instability of tape media, higher datatrack densities require a decreased physical spacing between data andservo tracks to ensure the accurate alignment of the read/write headswith the data tracks. The decreased spacing drives the need forincreased numbers of servo tracks which, in turn, must share the tapearea with data tracks. Furthermore, it is highly desirable for futuresystems to retain the ability to read the tapes made on earliersystems—this is termed “backward compatibility”. This backwardcompatibility requires the head positioning servos to be able to work ontapes with varying numbers of tracks and track configurations. Thispresents a design challenge and can force future drive designs to tradeoff between performance enhancements and backward compatibility. Afurther problem is that magnetically written servo tracks aresusceptible to track erasure. Bulk erasure of the tape can erase servotracks, drive system failure can result in the servo tracks beingoverwritten and corrupted—either of which can render the tape and itsdata useless.

[0004] There are numerous servo track systems in use in the field ofrewritable data storage media. Some of these are illustrated by thedisclosures of the following patents.

[0005] U.S. Pat. No. 4,958,245, titled “Apparatus And Method For OpticalServo Control With Media Having Information Storage And Servo ControlRegions Of Different Reflectivities” discloses an optical servo head toread position information from a disk on which data is magneticallyrecorded. The disk has a plurality of optical servo tracks formedthereon in the form of relatively nonreflective regions comprisingconcentric grooves formed in the reflective surface of the magneticdisk.

[0006] The servo system illuminates a plurality of the reflective andnon-reflective regions and uses a quadrature photodetector array toachieve tracking.

[0007] U.S. Pat. No. 5,067,039 titled “High Track Density Magnetic MediaWith Pitted Optical Servo Tracks And Method For Stamping The Tracks OnThe Media” discloses a method for mechanically stamping the servo trackson the optical disk during the disk manufacturing process.

[0008] U.S. Pat. No. 5,279,775 titled “Acousto-Optic Intensity ControlOf Laser Beam During Etching Of Optical Servo Information Of MagneticMedia” discloses a system that etches servo tracks on a magnetic disk.Track following during the etching process is accomplished by the use ofan acoustic-optical device to maintain the beam in concentric patterns,while a laser beam is used to etch the servo tracks, with the laser beamintensity being controlled by the acoustic-optical device

[0009] U.S. Pat.t No. 5,283,773 titled “Steering Laser Beam WhileEtching Optical Servo Tracks For Magnetic Disks” discloses a system thatetches servo tracks on a magnetic disk. Track following during theetching process is accomplished by the use of an acoustic-optical deviceto maintain the beam in concentric patterns, while a laser beam is usedto etch the servo tracks.

[0010] U.S. Pat. No. 5,462,823, titled “Magnetic Recording MaterialsProvided With A Photosensitive Layer” discloses a magnetic recordingelement that comprises a support layer coated with a magnetic recordinglayer and a photosensitive layer. Optical tracking information is formedon the photosensitive layer by the exposure of the photoreactive surfaceusing a servo track mask.

[0011] The above noted servo systems all make use of servo tracks thatare formed on the rewritable media on the same surface as is used tostore the data. The servo information is typically in the form of servotracks that are formed coextensive with the data tracks and interspersedamong the data tracks. Therefore, the servo tracks occupy space on thetape that can be used for the storage of data. Furthermore, there is aninherent interaction between the use of servo tracks and the writing ofdata tracks such that the system cannot optimize the data recordingfunction without impacting on the servo function. Conversely, the systemcan not optimize the servo function without impacting the data recordingfunction.

SOLUTION

[0012] The above described problems are solved and a technical advanceachieved by the present optical servo system for a tape drive thatfunctions to align a read/write head with the data tracks written on arecording surface of a tape by reading optical servo tracks that areformed on the back side of the tape. This process decouples the magneticrecording of data on the recording surface of the tape from the opticalservo system which makes use of servo tracks formed on the back side ofthe tape to position the read/write head. For example, the recordingformats of the data can be altered and the number of data tracks can bechanged without impacting the optical servo system. The servo system canaccommodate a wide range of recording format changes within its signalprocessing algorithms without modifying its servo tracks. In addition,the data storage capacity of the tape is increased since the entirerecording surface of the tape is filled with data tracks and precisealignment of the read/write head with the data tracks makes it possibleto place the data tracks closer together.

[0013] The tape used in this system has magnetic data tracks recorded onthe front side of the tape and optical servo tracks, comprising regionsof differing reflectivity or phase, formed on the back side of the tape.Although current magnetic media types could be utilized, the servo trackreading and writing processes explained below are optimized by the useof a media with a second side optically tuned to have high contrast orphase change at the read lumination wavelength and high writesensitivity at the servo track writing wavelength. A magnetic read/writehead that is positioned juxtaposed to the front side of the tape readsdata from and writes data to the data tracks while the optical servosystem reads servo data from the servo tracks that are formed on theback side of the tape. The requirement for close data track-to-servotrack spacing is met by having the servo tracks located immediatelybehind the data tracks. Regions of contrasting reflectivity or phase arealso provided on a surface of the read/write head to enable the opticalservo system to view an image of both the read/write head and the entireback side of the tape to thereby align the movable read/write head withthe data tracks. The head's optical features may be formed by numerousmeans known to those familiar with the art including integration intothe head structure itself or affixing a secondary structure to a headsurface. An optical sensor array generates electrical signals indicativeof the received image which are then used by a digital signal processorto determine the required alignment of the read/write head with the datatracks. Once the proper alignment is determined, the digital signalprocessor generates a position error signal that in turn is fed to theservo amplifier which drives an actuator to align the movable read/writehead with the data tracks.

[0014] The use of the two sources of optical data from the read/writehead and the tape media improves the accuracy, performance andreliability of the data track to read/write head alignment whilesimplifying the entire servo system. Using this approach, all opticalcomponents can be fixed in place. Since the servo system “closes theloop” around the tape and head optical feature alignment, systemalignment and calibration requirements are eased. Fault tolerance todamaged tape and/or head optical features is facilitated by theavailability of redundant optical information—a plurality of opticalfeatures exist on both the tape and the head. Furthermore, because thissystem locates the entire width of the tape with respect to the head,servo information is always available to quickly re-establishhead-to-tape alignment (i.e. “track following”) should it be lost duringdrive operations. Interchange, the ability to read a given tape on apopulation of tape drives, is facilitated by the servo system's abilityto image the mechanical relationship between tape and head immediatelyafter the tape is loaded into the drive and make appropriate offsetadjustments in the head's static position. The immediate availability ofthis offset information results in a reduced tape load time. Thisreduction, in turn, results in higher overall job throughput for thedrive in a repetitive tape loading environment - such as is commonlyseen when robots are used to mount and dismount tapes in the drive.

[0015] The optical servo tracks are not subject to magnetic erasure.Accidental magnetic damage is eliminated thus increasing data recoveryreliability. Bulk magnetic erasure of the tapes facilitates their reuseby reducing old data noise sources, improving data security byeliminating old data and providing an economic benefit over new tapes.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 illustrates in block diagram form the present optical servosystem for a tape drive;

[0017]FIG. 2 illustrates the waveform signal output from the imagesystem of the present optical servo system for a tape drive;

[0018]FIG. 3 illustrates in block diagram form the system for formingthe servo tracks on the tape for use by the present optical servo systemfor a tape drive; and

[0019]FIG. 4 illustrates in flow diagram form the operation of thepresent optical servo system for a tape drive.

DETAILED DESCRIPTION

[0020] The present optical servo system for a tape drive operates with atape that has data tracks written on a recording surface (first side) ofthe tape and optical servo tracks formed on the back side (second side)of the tape. An optical servo system reads the servo tracks on thesecond side of the tape and optical features on the read/write head todetermine the alignment between a read/write head with data tracks onthe first side of the magnetic tape. The digital signal processorgenerates control signals indicative of the adjustments needed to alignthe read/write head with the data tracks, the head actuator responds tothe amplified signals and moves the read/write head to the desiredposition.

[0021] Optical Servo System For A Tape Drive

[0022]FIG. 1 illustrates in block diagram form the present optical servosystem for a tape drive 600 and FIG. 4 illustrates in flow diagram formthe operation of this system. The present optical servo system for atape drive 600 operates to align tape 100 and read/write head 605 of thetape drive as tape 100 passes over read/write head 605. The remainingmechanical elements of the tape drive are not illustrated herein for thepurpose of simplicity of description. The read/write head 605 is movableand its position is determined by actuator 611, which operates undercontrol of the present optical servo system for a tape drive 600 asdirected by the drive processor 612. The tape 100, for the purpose ofthis description, is a magnetic tape that has a recording surface on afirst side 102 and a second side 101 that is used for positioninginformation. This process begins with the drive processor 612 issuing atrack position request at step 901.

[0023] The tape 100 has formed on the second side 101 thereof aplurality of parallel aligned servo tracks 110 that are used toprecisely identify the position of the data tracks written on the firstside 102 of the tape 100. The optical servo system for a tape drive 600reads one or more of the servo tracks 110 at the point that tape 100 isdirectly over read/write head's optical features 650. This isaccomplished by the Light Emitting Diodes (LEDs) 601-604 each generatinga beam of light that is directed onto tape 100 and read/write head 605by mirror 120. The servo tracks 110 formed on the second side 101 oftape 100 represent areas of differing reflectivity or phase and theimage of the second side 101 of tape 100 and the optical features 650 onthe face of the read/write head 605 extending beyond tape 100 isreflected back onto mirror 120. This reflected image is directed bymirror 120 through lens 606 onto sensor array 607. Sensor array 607 isan imaging device, such as a linear Charge Coupled Device (CCD) imagingarray, that functions to capture the reflected image and convert thereflected image into an electrical signals at step 902. The generatedelectrical signal, indicative of the image content, is transmitted tointerface circuit 615, which produces an analog signal that istransmitted to an analog to digital converter 608 to create a digitalrepresentation of the image at step 903. A digital signal processor 609receives this digital representation of the image and algorithmicallydetermines the alignment of the read/write head 605 with the data tracksfrom the digital image at step 904. The digital signal processor 609compares this current head position alignment with the drive processor'srequested position from step 901 and then determines the direction andthe distance that the read/write head 605 must be moved to meet the newposition request. The digital signal processor 609 at step 906 generatesa position error control signal that defines this movement and transmitsthe signal to a servo amplifier 610 at step 907 to control the operationof actuator 611 to move the read/write head 605 in the direction neededto align the movable read/write head 605 with the data tracks at step908.

[0024] While the read/write head 605 approaches the desired trackposition, the sensor array 607 continues to periodically update thetape-head image. This image signal is sent through processing blocks615, 608 to the digital signal processor 609. The digital signalprocessor 609 makes a new determination of read/write head alignmentthen reduces its position error signal to the servo amplifier 610accordingly to slow the actuator's movement of the head. This samplingprocess (steps 902-908) repeats itself until the head is in the desiredposition. At this point, the system “track follows” by continuing todetect small misalignments between the head and the desired track andsignaling the actuator 611 to make corrections to the head's position tokeep it precisely aligned (while still continuing to repeat steps902-908). This process continues until a new request (step 901) isreceived from drive processor 612 to move to a new track position. Thedrive processor's new position request is compared by the digital signalprocessor 609 (at step 904) to the current read/write head position anda new position error signal is generated (at step 906) and sent to theservo amplifier 610 (step 907). The actuator 611 begins to move theread/write head 605 (step 908) while the sensor array 607 allows theservo system to monitor progress toward achieving the new head positionby periodically updating the tape-head image. The image is sent throughprocessing blocks 615, 608 to the digital signal processor 609, wherethe position error signal is updated—this process repeats until the newhead position is attained and track following begins (steps 902-908).

[0025] As is known in the art, for fastest performance, the actuator'sacceleration is dependent upon the distance it is required totravel—large repositioning creates the largestacceleration/deceleration. Small track following re-positioning resultsin the smallest acceleration/decelerations and the greatest positionalprecision. In addition, the configuration disclosed herein isillustrative of the inventive concept and other optical configurationsare well within the design capabilities of one skilled in the art.

[0026] Image Content

[0027] An example of the image 700 captured by the present optical servosystem for a tape drive 600 is illustrated in FIG. 2. Image 700represents a sample of all of the pixels that are generated by sensorarray 607. For the purpose of illustration, the image size is selectedto be 5,000 pixels, with the horizontal axis of the diagram of FIG. 2representing the individual pixels, and the vertical axis representingthe signal magnitude of the selected pixel. The diagram also includesnotations along the top of the pixel chart to indicate the typicalextent of the tape 100 in the image 700. In addition, the image 700 isdivided into five regions: read/write head image 701, boundary betweenread/write head and tape image 702, tape image 703, boundary betweenread/write head and tape image 704, read/write head image 705. Thesevarious regions are individually discussed below.

[0028] Areas 701 and 705 are region of the read/write head image andcomprise approximately the first and last 500 pixels of image 700. Thevariations in signal strength illustrated by the continuous curve ofFIG. 2 represents the presence of the contrasting markings 650 locatedon the surface of read/write head 605. Since the read/write head 605 isthe sole source of this portion of the image, the variations are regularand map to the contrasting markings 650. Areas 702 and 704 represent theboundary between read/write head and tape image. An expanded view ofarea 702 illustrates the image received from the edge of tape 100.Within area 702, from about pixel 500 to about pixel 700, thecontrasting regions are from the contrasting markings 650 located on thesurface of read/write head 605 near the edge of tape 100. Region 712,from about pixel 700 to approximately pixel 900, indicates the edgeregion of tape 100 that does not contain optical data. Area 713 fromapproximately pixel 900 to approximately pixel 1200 has intermittentregions of high and low reflectivity or phase. In this example, theregions of low reflectivity indicate individual tracks of the servotrack group 110. Finally, area 703 includes pixels from approximatelypixel 1200 through approximately pixel 3800 and is an image ofcontrasting reflectivities or phases representing the servo tracks 110formed on the second side 101 of tape 100.

[0029] Method of Aligning

[0030] Applying conventional pattern recognition methods to image datafrom step 903, the digital signal processor 609 calculates the positionerror signal 906 by first establishing accurate measurements of therelative positions, in pixels, of the optical features found on themagnetic head and tape. Because of the tracking accuracy required by thetape drive may be more stringent than the pixel-to-pixel resolution inthe image data, sub-pixel measurement accuracy is needed. This accuracyis achieved by averaging the contributions to a given positionmeasurement from as many features in the image data as possible. Thedigital signal processor 609 must utilize all of the image data for themagnetic head optical features, 701 and 705, to yield an accuratemeasurement of the magnetic head position. Similarly, many opticaltracks 703 must be read and the data averaged to obtain an accuratemeasurement of a given magnetic track on tape. One method of utilizingall the data in an image subset is to use the correlation algorithmwhere an image subset is compared to a reference signal stored inmemory. The resulting correlation coefficient indicates a best fit when,the reference signal is optimally aligned with the image subset. Thereference signals can be based on typical signals experienced by manysuch tape drives and stored in non-volatile memory or can be based onactual signals obtained by a given tape drive during initial machinecalibration or periodic re-calibrations between tape loads.

[0031] Once the optical features are adequately determined, the magnetichead position is calculated by interpolation from those features, 701and 705. The magnetic track position is computed from the position of aplurality of the closest optical servo tracks from the set 703. Theposition error signal sent to the servo amplifier 610 at step 907 is thedifference between the calculated magnetic head position and the desiredmagnetic track position.

[0032] Additional Features

[0033] The optical servo system for a tape drive 600 can provideadditional capabilities beyond the provision of read/write headpositioning information. Auxiliary information formed on the second side101 of tape 100 can include encryption/authentication data, tapeidentification data or even maintenance information and read only data.For example, reflectivity or phase parameters can be recorded on tape100 to indicate the initial state of tape 100 as well as manufacturingdata. The optical servo system for a tape drive 600 can then measure thepresent optical characteristics of tape 100 to thereby obtain a measureof the wear on tape 100. Furthermore, optical servo system for a tapedrive 600 can view the image or read/write head 605 in its entiretybetween loads of tape 100 to verify head integrity and identify anyoptical feature defects.

[0034] The servo tracks 110 can perform a simple read/write headpositioning function or can be coded to provide data relating tolongitudinal positioning of tape 100 to enable high speed searching oftape 100, which data can also be used for tape velocity determination.This auxiliary information is encoded into the servo tracks during theservo track writing process using modulation that can be separated outfrom the basic servo signals by the digital signal processor 609. Theauxiliary information is then supplied to other drive or systemprocesses in step 909.

[0035] Servo Track Write System

[0036] A system for writing optical servo tracks 400 on tape 100 isillustrated in FIG. 3. The system for writing optical servo tracks 400writes the set of optical servo tracks 110 in one pass of tape 100through the system for writing optical servo tracks 400. The system forwriting optical servo tracks 400 includes a laser 415 that focuses abeam of light into beam expander 412. The expanded beam output by beamexpander 412 is extended through hologram 411 which splits the beam intoa plurality of individual beams 404-409, which are focused onto tape 100by lens 410. The exact number of beams is a design choice. However, theaccuracy of the alignment of the read/write head 605 and the second side101 of tape 100 improves as the number of optical servo tracks 110increases. Therefore, it is desirable to place as many servo tracks301-306 on tape 100 as possible. Increasing the number of servo tracksto be simultaneously written on the media is facilitated by the use ofmedia whose second side 101 is optically tuned to laser 415'swavelength. The plurality of beams 404-409 forms parallel aligned,optical servo tracks 301-306 onto the second side 101 of tape 100 astape 100 is passed under the beams 404-409. Rollers 401-403 move tape100 under the focused beams 404-409 at a constant speed on the secondside 101 of tape 100 to ensure that the optical servo tracks 110 havethe same consistency.

[0037] The laser beams 404-409 can be used to write auxiliary data onthe servo tracks 110 by programming laser 415 to intermittentlyextinguish. The intermittent extinguishing (modulation) of the beamcauses the servo optical tracks 110 to be written intermittently in aspecified pattern on side 101 of tape 100. This auxiliary data can beused by the present invention to determine tape speed, alignment, defectdetection and other attributes of the tape being read, as noted above.In the alternative, a plurality of lasers can be used to write theoptical servo tracks. The lasers could also be of different intensitiesto change the reflectivity or phase of individual tracks or the beamsfrom the lasers can be of varying widths to change the width of theformed servo tracks to allow recognition of different sections of tape.

What is claimed is:
 1. In a tape drive, a system for aligning aread/write head with a selected set of a plurality of data trackswritten on a first side of a tape as said tape passes over saidread/write head, wherein said tape also includes optical servo featuresformed on a second side of said tape, said system comprising: means forreading said optical servo features from said second side of said tape;and means, responsive to said read optical servo features, for aligningsaid read/write head with said selected set of a plurality of datatracks on said first side of said tape.
 2. The system of claim 1 ,wherein said read/write head has a plurality of optical features formedthereon or affixed thereto, further comprising: means for reading saidoptical features from said read/write head; and wherein said means foraligning is responsive to said read optical servo features from saidsecond side of said tape and said read optical features from saidread/write head.
 3. The system of claim 2 wherein said means for readingsaid optical servo features and said means for reading said opticalfeatures comprise: means for illuminating said optical servo features onsaid second side of said tape and said optical features of saidread/write head; means for reading an image of said optical servofeatures on said second side of said tape and said optical features ofsaid read/write head; means for generating electrical signals indicativeof said optical servo features on said second side of said tape and saidoptical features on said read/write head from said read image.
 4. Thesystem of claim 3 wherein said means for reading said optical servofeatures and said means for reading said optical features furthercomprise: means for focusing said optical servo features on said secondside of said tape and said optical features on said read/write head onto an imaging device to obtain electrical signals indicative of saidimage.
 5. The system of claim 3 , wherein said means for aligningcomprises: means, responsive to data track position data received from acontroller of said tape drive, for identifying a position of saidselected set of said plurality of data tracks in said plurality of datatracks; means, responsive to said generated electrical signals, fordetermining a position offset between said read/write head and saidselected set of said plurality of data tracks.
 6. The system of claim 5, wherein said means for aligning further comprises: means, responsiveto said means for determining, for generating a position error signal toindicate a direction and magnitude of said position offset.
 7. Thesystem of claim 6 wherein said means for aligning further comprises:means, responsive to said position error signal, for moving saidread/write head to adjust said alignment of said selected set of saidplurality of data tracks of said tape and said read/write head.
 8. Thesystem of claim 1 , wherein said second side of said tape has formedthereon auxiliary information from the class of tape auxiliaryinformation including but not limited to: encryption/authenticationdata, tape identification data, maintenance information, read only data,said system further comprising: means for reading said auxiliaryinformation from said second side of said tape; and means fortransmitting said read auxiliary data to a controller of said tapedrive.
 9. In a tape drive, a method for aligning a read/write head witha selected set of a plurality of data tracks written on a first side ofa tape as said tape passes over said read/write head, wherein said tapealso includes optical servo features formed on a second side of saidtape, said system comprising the steps of: reading said optical servofeatures from said second side of said tape; aligning, in response tosaid read optical servo features, said read/write head with saidselected set of a plurality of data tracks on said first side of saidtape.
 10. The method of claim 9 , wherein said read/write head has aplurality of optical features formed thereon or affixed thereto, furthercomprising the step of: reading said optical features from saidread/write head; and wherein said step of aligning is responsive to saidread optical servo features from said second side of said tape and saidread optical features from said read/write head.
 11. The method of claim10 wherein said step of reading said optical servo features and saidstep of reading said optical features comprise: illuminating saidoptical servo features on said second side of said tape and said opticalfeatures of said read/write head; reading an image of said optical servofeatures on said second side of said tape and said optical features ofsaid read/write head; and generating electrical signals indicative ofsaid optical servo features on said second side of said tape and saidoptical features on said read/write head from said read image.
 12. Themethod of claim 11 wherein said step of reading said optical servofeatures and said step of reading said optical features furthercomprise: focusing said optical servo features on said second side ofsaid tape and said optical features on said read/write head on to animaging device to obtain electrical signals indicative of said image.13. The method of claim 11 , wherein said step of aligning comprises:identifying, in response to data track position data received from acontroller of said tape drive, a position of said selected set of saidplurality of data tracks in said plurality of data tracks; anddetermining, in response to said generated electrical signals, aposition offset between said read/write head and said selected set ofsaid plurality of data tracks.
 14. The method of claim 13 , wherein saidstep of aligning further comprises: generating, in response to said stepof determining, a position error signal to indicate a direction andmagnitude of said position offset.
 15. The method of claim 14 whereinsaid step of aligning further comprises: moving, in response to saidposition error signal, said read/write head to adjust said alignment ofsaid selected set of said plurality of data tracks of said tape and saidread/write head.
 16. The method of claim 9 , wherein said second side ofsaid tape has formed thereon auxiliary information from the class oftape auxiliary information including but not limited to:encryption/authentication data, tape identification data, maintenanceinformation, read only data, said method further comprising the stepsof: reading said auxiliary information from said second side of saidtape; transmitting said read auxiliary data to a controller of said tapedrive.